Two-cycle pump and engine assembly



Sept. 30, 1952 J. R. EVANS 2,612,149

TWO-CYCLE PUMP AND ENGINE ASSEMBLY Filed Oct. 6, 1950 2 SHEETSSHEET 1 INVENTOR. JOJZ-PH A. Fm/vs Sept. 30, 1952 J. R. EVANS 2,612,149

TWO-CYCLE PUMP AND ENGINE ASSEMBLY Filed Oct. 6, 1950 2 SI-lEETS--SHEET 2 IN VEN TOR.

jasg /v I? fwwvs BY 772? Ala/Wm WW2 A? TQANEYS Patented Sept. 30, 1952 TWO-CYCLE PUMP AND ENGINE ASSEMBLY Joseph R. Evans, Lincoln, Nebr. Application October 6, 1950, Serial No. 188,795

This invention app ains to improvements in a two-cycle internal combustion engine and particularly to a novel construction of the cylinders and means for forcing a charge under pressure into the cylinders.

' A primary object of this invention is to provide a. sleeve pump piston for charging a cylinder, thus obviating the employment of inlet valves, camshafts and other attendant components.

Anotherobject of this invention is to provide apumping and compressing cylinder and piston for each working cylinder wherein the charge is compressed before being introduced into the cylinder for firing, thus providing economical and eflicient operationv and also resulting in an increase of power. I

These; and ancillary objects and attendant structural features of merit are. attained by this invention, the preferred embodiment of which is set forth in the following description and in the accompanying drawings, wherein:

Figure 1 is a longitudinal vertical sectional view through an, engine embodyingthe instant invention; I

Figure 2 is a transverse sectional view taken on 11ne 2- -2 of Figure -1;

Figure 3 is an exploded perspective view of the pu p pis Figure 4 is a diagram of the timing of the working and charging pistons on the crankshaft, and, 1 1 t Figure 5 is a cross sectional view takenon line 5.5 of Figure 1.

Referring now more particularly to the accompanying drawings, a crankcase I is illustrated, in the, opposing end walls of which a crankshaft I2 is journaled, with an ignition distributor [4 being conventionally associated with one end-of the crankshaft. An oil pump i6 is provided and a conduit communicates the pump with the crankcase. Longitudinally spaced walls i8 and 20 project upwardly from the crankcase and define cylinder assemblies 22 with the end walls of the crankcase. Each cylinder assembly 22 consists of a working cylinder 24 and a pumpingand cornpressing cylinder 26, which serves as a supercharger for the working cylinder. The cylinders 24 are provided with jackets 28 forming cooling chambers for air or waterto cool the cylinders.

Heads 30 and 32- close ofi the upper ends of the working and charging cylinders, respectively. PiS Qns 34, having conventional compression rings; are workably disposed in the working cylin ders 24 and are connected by connecting rods to the-cranksofthecrankshaft, th rods be- 4 Claims. (01. 123-70) mitted into the charging chamber 19 new;

lng afiixed by transverse wrist pins 38 ,to the pistons. Spark plugs 40 are mounted 'in the heads 36 of the working cylinder above the combustion chambers 42 and exhaust ports 44are formed in the side walls of the cylinders, the ports having suitable connections 46 for com munication with the exhaust manifold. ""flj f- Within the upper ends of each'of the charging or pumping and compressing cylinders 26, a hollow piston 48 is fixed, the piston "dependingifroin the head 32 and having its walls concentrically spaced out of engagement with the w'allsof the cylinder 26. The lower end of the fixed piston is closed by an. end wall 56 which includesjwith a longitudinally extending semicircular portion 52, forming an extension and lying in adjacency to the companion firing cylinder. f

A pumping and compressing piston 54 is work'- ably housed in the lower portion ofeachofthe charging cylinders and isformed with an open lower end 56 for thereception of 'aconnectin'g rod 58 journaled on the crankshaft behind the cranks receiving the rods for thefi'ringposition's, the pistons 54 being timed on the shaft'flfor stroking ahead of the firing pistonsyas will' be explained. l 'jjgg' A top wall 66 is formed on each of the pistons 54 and is formed to mate with the endwaflf52 of each of the fixed pistons 48,. ,Thus, thewaH 66 is'formed with an axially projecting semicir cular extension or longitudinallystepped portion 62. extends axially fromva portionjof the sidef wallof each of the pistons 54 and constitutes a prolonga tion of a portion of the side wall, the sleeveslida bly fitting between the fixed piston's and the cylinder walls. j,

A fuel line 66 communicatesv with each of e charging cylinders 26 by means of an intake port as in the side walls'of the cylinders; 'Air-isfad the fixed and movable pistonsfinjthe char cylinders 26 through the intakeor'inletjjpor 6B and is admixed with the fuel, th mixtiire be ffg compressed by the pumping.pistonadvanc g relative to the fixed; piston 4.8}Q10f cofurs separate air inlet could be provided-inlthe'jcy der wall and in communicationwith' .thfe" ber 10. r I a g 1 In Figure 1, the piston 34A'is 'illustr'at firing position, with theflpistonjt iB 'in pression positionand-the 'pis'tonf34C a th of the exhaust stroke. In this relativep will be noted that "the pumping an'dcomp pistons 54 are timed on-the crankshaft? ppro A semicircular (in, cross 'section).jsleeve" 64 3 mately 28 ahead of the firing pistons, as the crankshaft rotates, as illustrated in Figure 4.

Thus, in operation, fuel is admitted into the charging chambers Ill through the intake ports 68 on the suction or intake stroke of the pistons 54 with air being admitted into the chambers through the same ports. The pistons 54 initiate their intake strokes, as the cylinders 24 are as seen with respect to piston 34A and the companion piston 54. The air is admitted immediately upon the initiation of the downward or suction stroke and when the sleeve uncovers the intake port 68 in the side of the cylinder, and the fuel is also sucked into the chamber for admixing with the air. As seen with respect to piston 340, the piston 54 is initiating its compression stroke, as the working-piston 34C is at the end of its exhaust stroke, the sleeve closing ofi the fuel intake port.

The sleeve also, in the compression stroke of the pumping and compressing piston 54, closes on an opening 16 in the wall of the firing cylinders, which opening communicates "the firing chamber with the compression chamber.

At the end of the compression stroke of the piston '54, the piston 34B is compressing. Slight- .ly before that, the charge compressed by the piston 54 is transferred through the connecting passage or opening 16 into the firing chamber in the ffiringcy'linders, the sleeve being formed at its lower end with an opening 18 for this purpose. The pistons 34 close "off the openings it, as seen in the showing of piston 3418.

Thus, the opening i6 is closed off either by the pistons or the sleeve except when the sleeve opening 18 aligns therewith for a transfer of the compressed charge.

An opening 14 is transversely formed in the side wall of each piston 48 and a vertical opening T2 is formed in the extended bottomwall '52, the openings being provided to relieve the heads"3'2 since a portion of the charge would .possibly be compressed by the sleeve 61% moving ,in the space between the cylinder wall and piston wall. such compression would result in blowing the heads off but with theopenings pro-,

vided the small compressed "charge would be exhau'sted back into the chamber 10.

Having described the invention, what is claimed is: 1. In an internal combustion engine, a working cylinder, a piston working in said cylinder, a crankshaft, a "connecting rod connecting the piston to a, crank of the shaft, a charging cylinder disposed alongside the working cylinder and having fuel and air intake ports, a passage providing communication between the cylinders, a piston fixed at one end of the charging cylinder and spaced out of engagement with the walls thereof, said piston having a stepped end, a movable pumping piston Working in the chargingc'ylinder and connected to the crankshaft for reciprocation ahead of the piston in the working cylinder, a sleeve formed on the movable piston and extending'axially therefrom as a prolongation o'ffthe sidewall thereof, said sleeve being arranged to close off said passage and slidably engage between the wall of the charging cylinder and the fixed piston, a stepped end on the movable piston complementary to the stepped end of the 'fixed piston and arranged to mate therewith on the compression stroke 'ofthe movable piston'for compressing fuel therebetween,

andmeans formed in thesleev'e fortransferring the compressed fuel to the firing chamber 4 through said passage as the working piston is in its compression stroke.

2. In an internal combustion engine, a working cylinder having a head, a piston working in said cylinder, a crankshaft, a connecting rod connecting the piston to a crank of the shaft, a charging cylinder disposed alongside the Working cylinder and having a fuel intake port and an air inlet, a passage providing; communication between the cylinders, a piston fixed at one end of the charging cylinder and spaced out of engagement with the walls thereof, said piston having a stepped end, a movable pumping piston-working in "the charging cylinder and connected to the crankshaft for reciprocation ahead of the piston and the working cylinder, a sleeve formed on the movable piston and extending axially therefrom as a prolongation of the side wall thereof, said sleeve being arranged to close oif said passage and slidably engage between the wall of the charging cylinder" and the fixed piston, a stepped end on the movable piston complem'entary to the stepped end 'of the fixed piston and arranged to mate therewith on the'compr'e'ssion stroke of the movable piston for compressing fuel therebetween, means formed in the "sleeve for transferring the compressed fuel "to the firing chamber through said passage as the working piston is in its compression stroke, an exhaust port formed in the working cylinder, andignition means carried by the head of said Working cylinder.

3. In an internal combustion engine, a working cylinder, a piston workingin said cylinder, 41 crankshaft, a connecting rod connecting the-piston to a crank of the shaft, a charging-cylinder disposed alongside of the working cylinder and having a fuel and air intake port, a passage roviding communication between the 'cylin'ders,-a piston fixed at one end 'of"'the charging cylinder and spaced out of engagement with the walls thereof, said fixed piston having a stepped end, a movable pumping piston working in thecharging cylinder and connected to the crankshaft for reciprocation ahead-of the piston in-the work-ing cylinder, a sleeve formed on 'the movable piston and extending axially therefrom as a prolongation of the side wall thereof, said' sleeve being arranged to close on saidpassage andslidably engage between the wall of the charging cylinder and the fixed piston, a stepped end on the movable piston complementary to the steppedend of the fixed piston and arranged to mate therewith on the compression stroke of the movable piston for compressing fuel therebetween, said sleeve having a transverse opening" in the end thereof adjacent to the movablep'isto'n', the opening being 'registrable with said passage'f'or transferring-fuel compressed in the charging "cylinder -into'- the working cylinder. 1 r

4. In an internal combustion engine; a working cylinder having a workingpiston operating there-'- in, a charging cylinder, a fixed pistonin one-end of said charging cylinder, said fixed piston-being spaced from the side-wall of said charging cylinder,-a movable fuel compressingpistonoperating in said charging cylinder between said fixed-pin ton and to -the other end of the charging cylinder, a fuel charging port leading from said charging cylinder into said working cylinder from a-point in said'charging cylinder between said fixed and movable pistons, a sleeve on said movable piston positioned in the space between said fixedpiston and the side wall of said charging" cylinder, said working piston being "arranged to ciese said charging port in an inner position of said working piston and said sleeve being arranged to close said charging port in one position of said movable piston and having an opening arranged toregister with said charging port to uncover said charging port in another position of said movable piston, a fuel inlet port leading into said charging cylinder at a point between the fixed and movable pistons therein, exhaust means for the working cylinder, and operating means connecting said working piston and said compressing piston for coordinated operation, said charging port and said fuel inlet port being longitudinally spaced from each other with respect to the length of the charging cylinder, said fixed and movable pistons having facing ends, and mated step extensions on said ends, the end of the fixed piston terminating at one side of the fuel inlet port and the step extension of the fixed piston terminating at the same side of the charging port, the end of the movable piston being arranged to approach the step extension of the fixed piston and partially close said charging port with the step extension of the movable piston approaching the end of the fixed piston and closing said fuel inlet port on the compressing stroke of said movable piston whereby fuel is compressed in said charging cylinder and charged into said working cylinder through said sleeve opening and said charging port.

JOSEPH R. EVANS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

